1. Field of the Invention
The invention relates to a damping force device with adjustable damping force.
2. Discussion of the Prior Art
German reference DE 196 37 095 C2 discloses a vibration damper with variable damping force, in which the damping force is adjustable as a function of the compression travel. As soon as an axle part expands, for example on a bend, there is no damping force adjustment carried out. In the embodiment of the vibration damper according to DE 196 37 095 C2, there is a tendency toward a softer setting of the damping force, since the adjustable damping valve is not additionally pressurized. It was found that it is expedient, on a bend, also to set the vibration damper on the bend-inside wheel with a greater damping force, in order to prevent the wheel from jumping. In vibration dampers, the damping force of which can be adjusted via an electric actuator, the problem of how to set the bend-inside vibration damper with a greater damping force does not arise. Suitable sensor technology allows a controlled setting of the damping force on the basis of many different parameters which characterize the movement of the vehicle and/or of the wheel. By contrast, sensor technology cannot be used in a vibration damper, such as is known, for example, from DE 196 37 095 C2.
The object of the present invention is to provide a damping device, in which it is possible to adjust the damping force, in particular during a rolling movement of a motor vehicle, and the problems known from the prior art are avoided.
The object is achieved, according to the invention, in that the generator device comprises an equidirectional device which causes an equidirectional regulating variable to take effect on the adjustable damping valve independently of the compression direction.
It is thereby possible that the generator device can be designed in a very simple way. Whether a compression movement or an expansion movement of the wheel is taking place is less important for the damping device.
So that as few regulating or transmission elements as possible need to be used, the generator device is connected to a stabilizer. The stabilizer, by virtue of its principle, has one movement behavior in the case of a suspension movement of the wheels in the same direction or in the case of a suspension movement in a different direction, for example in the case of unilateral compression or on a bend. This movement behavior allows a controlled variation of the damping force in specific compression situations.
In a first embodiment, the generator device is designed as a gear with coupling rods, an output coupling rod exerting a unilaterally directed regulating force independently of an input coupling rod.
With a view to as few gear parts as possible, the stabilizer forms the input coupling rod.
Furthermore, there is provision for the gear to have a coupling rod which is designed as a rocker and on which further coupling rods engage.
In addition, a coupling rod has free motion for one force transmission direction in each case, so that the coupling rods within the gear can transmit a regulating force in only one direction.
In an alternative embodiment, the equidirectional device has for each compression direction at least one working space filled with pressure medium, the pressure medium being conveyed into a control space of the adjustable damping valve through at least one pressure medium line by a displacer.
In order to minimize the use of nonreturn valves and at the same time achieve the safeguarded functioning of the equidirectional device, there is provision for each working space to have a separate displacer, so that the movement of one displacer can be executed independently of a second displacer.
In this case, the displacers assume their maximum stroke position when the vibration damper is in a defined compression position. Strict functional separation of the displacers is achieved by means of this measure. In a different compression position, only one displacer is moved and ensures that pressure medium is conveyed to the control space of the adjustable damping valve.
In addition, the two working spaces have a separate pressure medium line to the control space, the pressure medium lines containing a throttle device. Different throttle settings can be carried out for each suspension direction by means of separate pressure medium lines. In principle, if this possibility is to be dispensed with, the pressure medium lines of the working spaces could be connected to one another and only one common pressure medium line to the control space of the adjustable damping valve be provided.
In order to simplify the outlay for the construction of the equidirectional device, the working spaces are arranged in a common housing.
Thus, there may be provision for the stabilizer to have a split design, one stabilizer portion being connected fixedly in terms of rotation to a pivoting generator shaft and a second stabilizer portion being connected fixedly in terms of rotation to the housing, and a displacer conveying pressure medium to the vibration damper within the housing as a result of the relative movement between the housing and the pivoting generator shaft.
So as not to give rise to damping force adjustment on the adjustable damping valve whenever there is a slight suspension movement, the working movement of the displacer for the reduction of the working space is counteracted by a threshold-force.
With a view to as favorable a utilization of the construction space as possible, the threshold-force is arranged within the working space.
So that a softer damping force setting on the adjustable damping valve does not occur too quickly in the event of a reversal of the suspension movement, the pressure medium flows out of the control space of the adjustable damper through the throttle device back into the working space.
For a rapid response to the adjustable damping valve, a nonreturn valve is connected in parallel to the throttle device.
So that the overall outlay for adjusting the damping force for vibration damping can be kept low, a plurality of vibration dampers of one vehicle axle are connected to the equidirectional device.
In a further development stage, a plurality of vibration dampers of a plurality of vehicle axles may also be connected to the equidirectional device.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.